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Description: Analytical methods for determining formic and oxalic acids, formaldehyde and methanol have been evaluated and/or optimized for measuring products from photoreduction of CO{sub 2} in illuminated, aqueous suspensions of photocatalysts. An electrophoretic analysis method can detect aqueous formate and oxalate ions at 3 and 1 {micro}M respectively. Recalibration of the Nash formaldehyde determination shows that as little as 0.5 {micro}M can be detected spectrally. Several experiments using suspensions of TiO{sub 2}, SrTiO{sub 3} and SrTiO{sub 3} with Cr and Sb were tested in CO{sub 2} saturated solutions. No formate was detected in most experiments. However adding 2-propanol to a CO{sub 2}/TiO{sub 2} suspension gave significant amounts of formate and some formaldehyde by blocking the re-oxidation of formate by semiconductor holes. Loss of C{sub 1} products by re-oxidation is probably an important process limiting the accumulation of formate, formaldehyde and methanol.
Date: March 13, 2003
Creator: Mill, Theodore & Tungudomwongsa, Haruthai
Partner: UNT Libraries Government Documents Department

Directed synthesis of crystalline plutonium (III) and (IV) oxalates: accessing redox-controlled separations in acidic solutions

Description: Both binary and ternary solid complexes of Pu(III) and Pu(IV) oxalates have been previously reported in the literature. However, uncertainties regarding the coordination chemistry and the extent of hydration of some compounds remain mainly because of the absence of any crystallographic characterization. Single crystals of hydrated oxalates of Pu(III), Pu{sub 2}(C{sub 2}O{sub 4}){sub 3}(H{sub 2}O){sub 6}{center_dot}3H{sub 2}O (I) and Pu(IV), KPu(C{sub 2}O{sub 4}){sub 2}(OH){center_dot}2.5H{sub 2}O (II), were synthesized under moderate hydrothermal conditions and characterized by single crystal X-ray diffraction studies. Compounds I and II are the first plutonium(III) or (IV) oxalate compounds to be structurally characterized via single crystal X-ray diffraction studies. Crystallographic data for I: monoclinic, space group P21/c, a = 11.246(3) A, b = 9.610(3) A, c = 10.315(3) A, Z = 4 and II: monoclinic, space group C2/c, a = 23.234(14) A, b = 7.502(4) A, c = 13.029(7) A, Z = 8.
Date: January 1, 2009
Creator: Runde, Wolfgang; Brodnax, Lia F; Goff, George S; Bean, Amanda C & Scott, Brian L
Partner: UNT Libraries Government Documents Department

Regulation of Coal Polymer Degradation by Fungi

Description: Previous studies in our laboratory used a spectrophotometric assay to study biomimetic solubilization of leonardite by sodium oxalate. It was found, however, that in extended incubations of several days, this assay resulted in overestimation of the percent of leonardite that was solubilized. This problem did not appear to be significant for short term incubations (ie., up to -24 h) and was circumvented in long term incubations by using a gravimetric assay to assay for solubilization. In other studies during this reporting period we examined oxalate production by P. chrysosporium and T. versicolor grown in Fahreus-Reinhammar medium in agitated pelleted culture. It was found that in this system concentrations of oxalate are produced that are much lower than those that would be optimal for leonardite solubilization.
Date: April 30, 1997
Creator: Irvin, R.L. & Bumpus, J.A.
Partner: UNT Libraries Government Documents Department

Plutonium(IV) oxalate precipitation and calcination process for plutonium nitrate to oxide conversion

Description: The Plutonium(IV) Oxalate Precipitation and Calcination Process for converting plutonium nitrate to plutonium oxide is described for a 100-kg plutonium per day (Pu/day/ throughput facility. Block flow diagrams, equipment flowsheets, and stream material balances are included. Advantages and disadvantages of the process, additional research and development necessary, and history of the process are also discussed. This report is one of a series describing various processes for converting plutonium nitrate to oxide. This information in this report should be used when comparing the various processes, and as a starting point for development of a prototype or plant-scale facility.
Date: July 26, 1978
Creator: Greintz, R.M. & Neal, D.H.
Partner: UNT Libraries Government Documents Department

Density of simulated americium/curium melter feed solution

Description: Vitrification will be used to stabilize an americium/curium (Am/Cm) solution presently stored in F-Canyon for eventual transport to Oak Ridge National Laboratory and use in heavy isotope production programs. Prior to vitrification, a series of in-tank oxalate precipitation and nitric/oxalic acid washes will be used to separate these elements and lanthanide fission products from the bulk of the uranium and metal impurities present in the solution. Following nitric acid dissolution and oxalate destruction, the solution will be denitrated and evaporated to a dissolved solids concentration of approximately 100 g/l (on an oxide basis). During the Am/Cm vitrification, an airlift will be used to supply the concentrated feed solution to a constant head tank which drains through a filter and an in-line orifice to the melter. Since the delivery system is sensitive to the physical properties of the feed, a simulated solution was prepared and used to measure the density as a function of temperature between 20 to 70{degrees} C. The measured density decreased linearly at a rate of 0.0007 g/cm3/{degree} C from an average value of 1.2326 g/cm{sup 3} at 20{degrees} C to an average value of 1.1973g/cm{sup 3} at 70{degrees} C.
Date: September 22, 1997
Creator: Rudisill, T.S.
Partner: UNT Libraries Government Documents Department

Photolytic destruction of oxalate in aqueous mixed waste

Description: In aqueous plutonium processing, residual oxalic acid can be destroyed (oxalate kill) by UV light with hydrogen peroxide (H{sub 2}O{sub 2}) in 1 M HCl solutions. By controlling the amount of H{sub 2}O{sub 2}, the oxalate kill process will not affect the chloride concentration. In nitric acid solutions, UV light alone can destroy the oxalic acid. However, with H{sub 2}O{sub 2}, the rate of destruction is faster. After the destruction of oxalic acid, the acidic solutions may be reusable without further purification process.
Date: March 1, 1995
Creator: Wang, F.T. & Lum, B.Y.
Partner: UNT Libraries Government Documents Department


Description: for filtration of plutonium oxalate slurries. A scalpel produces a slit in the filter precoat, leading to increased filtration in this slit, and the oxalate is removed by a doctor knife; this technique results in prolonged blowback cycles and more uniform delivery of filtered oxalate to subsequent processing steps. Several types of filter media were tested, and rigid porous aluminum oxide was found to be the best one. (D.L.C.)
Date: October 19, 1959
Creator: Rey, G.
Partner: UNT Libraries Government Documents Department

Preparation of Americium Dioxide by Thermal Decomposition of Americium Oxalate in Air

Description: One hundred and seventy five grams of americium in a hydrochloric acid solution varying from 1 to 7 N was converted to americium dioxide. Americium oxalate was precipitated from 0.1 N HCI with 100% excess oxalic acid and was converted to the dioxide by calcination at 800 ts C in air. The solubility losses in the oxalate precipitation filtrate averaged approximately 7 mg/liter of solution, with a total loss of 0.09%. (auth)
Date: December 20, 1960
Creator: Baybarz, R. D.
Partner: UNT Libraries Government Documents Department

Lithium Methyl Carbonate as a Reaction Product of Metallic Lithiumand Dimethyl Carbonate

Description: To improve the understanding of passive film formation on metallic lithium in organic electrolyte, we synthesized and characterized lithium methyl carbonate (LiOCO{sub 2}CH{sub 3}), a prototypical component of the film. The chemical structure of this compound was characterized with Nuclear Magnetic Resonance (NMR) and Fourier Transform Infrared Spectroscopy (FTIR), and its thermal stability and decomposition pathway was studied by thermo-gravimetric analysis (TGA). The FTIR spectrum of chemically synthesized compound enabled us to resolve multiple products in the passive film on lithium in dimethyl carbonate (DMC). Lithium methyl carbonate is only one of the components, the others being lithium oxalate and lithium methoxide.
Date: October 16, 2005
Creator: Zhuang, Guorong V.; Yang, Hui; Ross Jr., Philip N.; Xu, Kang & Jow, T. Richard
Partner: UNT Libraries Government Documents Department


Description: The literature has been reviewed in December 2011 for calcination data of plutonium oxide (PuO{sub 2}) from plutonium oxalate Pu(C{sub 2}O{sub 4}){sub 2} precipitation with respect to the PuO{sub 2} specific surface area (SSA). A summary of the literature is presented for what are believed to be the dominant factors influencing SSA, the calcination temperature and time. The PuO{sub 2} from Pu(C{sub 2}O{sub 4}){sub 2} calcination data from this review has been regressed to better understand the influence of calcination temperature and time on SSA. Based on this literature review data set, calcination temperature has a bigger impact on SSA versus time. However, there is still some variance in this data set that may be reflecting differences in the plutonium oxalate preparation or different calcination techniques. It is evident from this review that additional calcination temperature and time data for PuO{sub 2} from Pu(C{sub 2}O{sub 4}){sub 2} needs to be collected and evaluated to better define the relationship. The existing data set has a lot of calcination times that are about 2 hours and therefore may be underestimating the impact of heating time on SSA. SRNL recommends that more calcination temperature and time data for PuO{sub 2} from Pu(C{sub 2}O{sub 4}){sub 2} be collected and this literature review data set be augmented to better refine the relationship between PuO{sub 2} SSA and its calcination parameters.
Date: March 6, 2012
Creator: Daniel, G.
Partner: UNT Libraries Government Documents Department

Purification of 238Pu Oxide using the Pu Oxalate Process

Description: The Pu oxalate process is used to remove {sup 234}U from aged {sup 238}Pu-enriched PuO{sub 2} ({sup 234}U grows into the PuO{sub 2} material with time from a-decay of {sup 238}Pu). The Pu oxalate process was first used on a mixture of weapons grade PuO{sub 2} with UO{sub 2} to work out the processing parameters. It was then applied to aged {sup 238}Pu-enriched PuO{sub 2} ({sup 238}PuO{sub 2}). The {sup 234}U content of the {sup 238}PuO{sub 2} was reduced from 13.2 wt% to 0.0254 wt%, and the Pu recovery yield was 78.5%. The process is complex and is complicated by radiolysis problems when working with {sup 238}Pu. Details of the experiments are described.
Date: November 28, 2001
Creator: Mew, D A; Krikorian, O H; Dodson, K E & Schmitz, J A
Partner: UNT Libraries Government Documents Department

Technology development for iron Fischer-Tropsch catalysts. Technical progress report No. 5, September 26, 1991--December 26, 1991

Description: Objective is to develop producing active, stable iron Fischer-Tropsch catalysts for use in slurry-phase synthesis reactors and to synthesize such catalysts on a large scale for process development and long-term testing in slurry bubble-column reactors. A mixed oxalate of Fe, Cu, and K was prepared; a catalyst will be prepared from this material. An evaluation run was performed on an Fe-based UCI catalyst, which was shown to produce low levels of C{sub 1} and C{sub 2} paraffins; e.g., at the end of the run, when the catalyst was converting 60% of the CO, the C{sub 1} and C{sub 2} paraffin selectivities were 4.2 and 1.0, respectively.
Date: December 22, 1992
Creator: Frame, R. R. & Gala, H. B.
Partner: UNT Libraries Government Documents Department

Heterogeneous nucleation of calcium oxalate on native oxide surfaces

Description: The aqueous deposition of calcium oxalate onto colloidal oxides has been studied as a model system for understanding heterogeneous nucleation processes of importance in biomimetic synthesis of ceramic thin films. Calcium oxalate nucleation has been monitored by measuring induction times for nucleation using Constant Composition techniques and by measuring nucleation densities on extended oxide surfaces using an atomic force microscope. Results show that the dependence of calcium oxalate nucleation on solution supersaturation fits the functional form predicted by classical nucleation theories. Anionic surfaces appear to promote nucleation better than cationic surfaces, lowering the effective energy barrier to heterogeneous nucleation.
Date: April 1, 1994
Creator: Song, L.; Pattillo, M. J.; Graff, G. L.; Campbell, A. A. & Bunker, B. C.
Partner: UNT Libraries Government Documents Department

Thermodynamics of the Complexation of Uranium(VI) by oxalate in aqueous solution at 10-70oC

Description: The protonation reactions of oxalate (ox) and the complex formation of uranium(VI) with oxalate in 1.05 mol kg{sup -1} NaClO{sub 4} were studied at variable temperatures (10-70 C). Three U(VI)/ox complexes (UO{sub 2}ox{sub j}{sup (2-2j){sup +}} with j = 1, 2, 3) were identified in this temperature range. The formation constants and the molar enthalpies of complexation were determined by spectrophotometry and calorimetry. The complexation of uranium(VI) with oxalate ion is exothermic at lower temperatures (10-40 C) and becomes endothermic at higher temperatures (55-70 C). In spite of this, the free energy of complexation becomes more negative at higher temperatures due to increasingly more positive entropy of complexation that exceeds the increase of the enthalpy of complexation. The thermodynamic parameters at different temperatures, in conjunction with the literature data for other dicarboxylic acids, provide insight into the relative strength of U(VI) complexes with a series of dicarboxylic acids (oxalic, malonic and oxydiacetic) and rationalization for the highest stability of U(VI)/oxalate complexes in the series. The data reported in this study are of importance in predicting the migration of uranium(VI) in geological environments in the case of failure of the engineering barriers which protect waste repositories.
Date: March 31, 2009
Creator: Di Bernardo, Plinio; Zanonato, Pier Luigi; Tian, Guoxin; Tolazzi, Marilena & Rao, Linfeng
Partner: UNT Libraries Government Documents Department

Optimization of air-sparged plutonium oxalate/hydroxide precipitators

Description: The high cost of waste management and experimental work makes numerical modeling an inexpensive and attractive tool for optimizing and understanding complex chemical processes. Multiphase {open_quotes}bubble{close_quotes} columns are used extensively at the Los Alamos Plutonium Facility for a variety of different applications. No moving parts and efficient mixing characteristics allow them to be used in glovebox operations. Initially, a bubble column for oxalate precipitations is being modeled to identify the effect of various design parameters such as, draft tube location, air sparge rate and vessel geometry. Two-dimensional planar and axisymmetric models have been completed and successfully compared to literature data. Also, a preliminary three-dimensional model has been completed. These results are discussed in this report along with future work.
Date: April 1, 1997
Creator: VanderHeyden, W.B.; Yarbro, S.L. & Fife, K.W.
Partner: UNT Libraries Government Documents Department